1. Field of the Invention
The present invention relates to a handheld electrocardiographic measurement device that acquires an electrocardiographic signal.
2. Description of the Related Art
In recent years, public interest in management, maintenance, and promotion of health has been growing. There is a demand that people can more easily obtain biological information, such as a pulse and an electrocardiographic information, in daily life. Japanese Unexamined Patent Application Publication No. 2013-226189 and Japanese Patent No. 5223967 each disclose an electrocardiographic measurement device to be held with both hands to acquire an electrocardiographic signal from palms or fingers of the hands.
More specifically, the device of Japanese Unexamined Patent Application Publication No. 2013-226189 includes a case having a peripheral surface to be held with both hands, and electrocardiographic electrodes for detecting an electrocardiographic signal through the hands holding the case. In particular, the case in this device is spherical, and a left-hand electrode and a right-hand electrode serving as electrocardiographic electrodes are provided in correspondence to the palms or fingers of both hands holding the case.
The electrocardiographic signal detection device of Japanese Patent No. 5223967 is a portable device, and detects an electrocardiographic signal from thumbs of both hands gripping the device. In more detail, the electrocardiographic signal detection device includes a housing made of an insulating material, such as resin. A display window is attached at an opening in an upper surface of the housing. Inside the display window, two electrodes are disposed to detect an electrocardiographic signal. The electrodes are disposed at positions such that the thumbs of both hands can easily touch the electrodes in a state in which the electrocardiographic signal detection device is gripped with the hands. That is, one of the electrodes is disposed on a left proximal side of an upper surface of the display window, and the other electrode is disposed on a right proximal side of the upper surface of the display window.
As described above, in the device of Japanese Unexamined Patent Application Publication No. 2013-226189, when the spherical case is held with both hands, the palms or fingers of the hands come into contact with the electrocardiographic electrodes (left-hand electrode and right-hand electrode), and this allows acquisition of an electrocardiographic signal. However, since this device is held with both hands from the left and right sides, for example, in a situation in which the device cannot be placed on a desk, when electrocardiographic measurement is continued for a long period (for example, about serval minutes), the hands holding the device get tired, and strain is applied to the hands and shoulders. As a result, there is a fear that myoelectric noise will be easily included in the electrocardiographic signal.
In contrast, the electrocardiographic signal detection device of Japanese Patent No. 5223967 is a portable device and can be reduced in size. However, both hands may touch each other during measurement. In this case, if both hands touch each other, the S/N ratio of the electrocardiographic signal may be decreased. However, if the touch of both hands is avoided, it may be difficult to grip the device. Moreover, since the electrocardiographic signal detection device is held while being clamped (pinched) by, for example, thumbs and forefingers, strain is easily applied to the hands, and myoelectric noise is easily included.